Determining the electrical connection

The present invention relates to a method and an apparatus for determining an electrical contact of an electrical system with a measuring system, the measurement system can be connected to measuring points of the electrical system on measuring contacts, as well as the use of the device.

For servicing electrical systems the freedom of the electrical system voltage be noted, can be made to this work before. The sole separating the electrical system from the electric supply network or from the electrical supply is not yet a secure basis, determine voltage freedom, since electrical energy can be stored in electrical energy storing nevertheless, such as capacitors, . Other electrostatic charges are also conceivable, which can lead to a low residual stress in the electrical system. But also a voltage measurement on the electrical system voltage freedom not guaranteed, not even then, if no voltage is detected. Due to possible error of the measurement at the measurement object contacts a contact measuring device, it can lead to erroneous display the voltage display a low residual stress freedom or, even though a (at the measurement object can certainly still concerns high) voltage. Also in an electrostatic charge due to the high impedance input of a voltage meter electrical system can lead to a low voltage display.

Also a very low voltage caused by a bad contact or a display can thus actually existing residual stress from the system.

Detecting the voltage for a secure freedom an electrical system, the electrical system in order to ensure that further work performing, testing the measurement contacts contacting of the measuring device is therefore necessary. In the case of incorrect contacting a lower voltage could, in the worst case no voltage are measured,, as actually rests between the measuring points, which is a potential risk for people, to conduct the work on the electrical system. Conventional measuring instruments but not offer this function. Therefore the contacting review was performed visually so far. I.e., the user visually examine, whether the measurement contacts properly contacting the measured object. In many applications, e.g. for vehicles with electrified drives, visual inspection of the contact but through the narrow space conditions or the position of the can not be carried out or not clearly measuring points. Further can be closed not always a visual contact on an actual electrical contacting.

The conceivable in measuring devices often use existing resistance measurement for a contact verification would be. This is a current or voltage source integrated in the measuring device by measuring the current flow and the measurement contacts - of the measuring device can be closed on a contacted measuring point. But only a purely ohmic and can thus also be detected only a low-ohmic resistor. A contacting error, equated with a high-resistance resistor, can in this way but not sure and determining undoubtedly. A high residual stress may lead to a destruction of the further measuring device, when the latter is in the resistance measurement mode.

It is therefore a task of the invention confers, specify a measuring system, allow easily determine with certainty, whether measuring contacts, at which a voltage measurement is to be carried out were, properly contacted.

This problem is solved, by closing a discharge switch which couples in the measuring system, a charging circuit including a voltage measuring device, the charging circuit on an internal resistance of the voltage meter discharges and discharge switch according to one closing a measurement switch is closed, which the voltage meter with the measurement contacts connects, the contacting of the electric system with the measuring system is determined, the voltage waveform is evaluated by measuring the voltage meter from closing the switch in an evaluation unit. The contacting of the electrical system can for example fully, partially or not be present. The voltage waveform at the voltage measuring device can also be displayed by a display unit.

An evaluation of the voltage waveform from closing the measurement switch can be for example the detection of a recess, which can be done e.g. by means of a differentiation of the voltage. It could also a target voltage waveform measured and compared with the actual voltage waveform. Also an integration of the voltage waveform would be one way, and so on.

But it can also advantageously be included after closing of the discharge switch and before closing the switch a characteristic voltage waveform of the measurement system by means of the measuring voltage measurement apparatus. The characteristic voltage waveform is compared with the voltage waveform after the closing of the measurement switch, which can be closed to contact.

The discharge of the charging circuit via the internal resistance of the voltage measuring apparatus is normally determined in. It is also possible for the discharging operation on a voltage meter discharge resistor connected to influence, which discharges the charging circuit also on the discharge resistor. This discharge resistor may be connected in series with the voltage meter both parallel also. In the case of a parallel connection of the total resistance of the circuit is decreased and the discharge process accelerated. In the case of a series circuit of total resistance is increased, whereby the discharge during a longer period. A discharge resistor in series but has the effect of a current limitation. Further influenced by the dimensioning of the discharge resistor is the time constant of the circuit. The charging circuit has usually capacitive components, an increase in the form of a series circuit of the discharge resistance increases the time constant circuit resistance and lowers to the flowing current equally. This can serve a current limitation. A discharge resistor causes a reduction of the circuit resistance and coupling the a lower time constant so that the voltage to be measured and thus faster from - or up-sound.

Advantageously the measurement switch is closed, the voltage measuring device when a voltage threshold is undershot. Thus resulting in damage to sensitive electronic measuring system can for example by current peaks are avoided.

The charging circuit can for example from a voltage source and a capacitor mounted in parallel up. This switch can connect the voltage source to the capacitor charging, wherein the charging process of the capacitor begins after closing the charging switch. As soon as the charging switch is then opened, a charge stored in the capacitor remains. The capacitor can be subsequently discharged after closing the discharge switch on the voltage measuring apparatus according to the invention and according to closing the measurement switch on the overall impedance of the interconnection upon successfully contacting from voltage measuring apparatus and measuring system.

It is also possible, to use the device such, after determining that a voltage at the measuring points successfully contacting, advantageously by the voltage present in the measuring circuit measuring apparatus. The purpose of the voltage at the measurement points can be determined after or during the determination of the contact from the voltage waveform.

A step of further can be measured at the measuring points of the electrical system the value of this voltage. This advantageously is carried out in the measuring circuit voltage measurement by existing stress gauge.

The invention is subsequently subject coding with reference to the figures 1 io 4 explained in more detail, the exemplary, schematically and not limitative, show advantageous configurations of the invention. It showed

Figure. 1 a meter connected to a electrical system,

Figure. 2 different profiles of the voltage U,

Figure. 3 a possible configuration of the gauge.

With reference to fig. 1. the basic process of the invention with a measuring system 2 according to the invention is described. An electrical system 1, e.g. an electric drive system of a hybrid vehicle, the voltage should be determined with a measuring device 2 freedom, work can be carried out before the electricity system 1.

The electricity system measuring points 1 to 3, e.g. measuring points are prepared, provided, for measuring a voltage of the voltage to contact the measuring contacts 4 of the measuring device 2 to eliminate any. In the measuring system 2 for example a conventional voltage meter V is for voltage measurement with internal resistance R (1 indicated in Fig.) provided. Determining a proper contacting the measuring device 2 is next to the safe voltage meter V to a charging circuit from the charging circuit 5 has a charge storage for storing 5th electric charge and can therefore represent for example a capacitance, an electrical energy store, etc... Of course any other type of energy source can be used. The charging circuit can be a discharge switch connected to the voltage s1 5 meter volts. So that the charging circuit 5 on the internal resistance R of the voltage meter volts, wherein the voltage measuring device V to the records from the inner resistance R of the measurement system discharges resulting characteristic voltage waveform LUar 2. The discharge switch remains closed and the measurement switch s1 subsequently s2 is closed, whereby the impedance of the entire system in the case of a correct contacting the measuring points 3 changes the electric system 1, consisting of measuring system 2, i.e. voltage meter V with internal resistance R is positive charging circuit 5, and electrical circuit 2. The course of the voltage V at the voltage measuring device and after closing of the measurement switch before the U s2 can be closed in a proper contact.

The characteristic voltage waveform in Figure LUar is. 2a represented. The discharge switch time T I is closed and the voltage curve at the voltage meter ab. s1 sounds is 1 does not contact the electrical system, for example when a measuring contact 4 or at least not fully at the measuring location 3 bears, such follows the course of the voltage U at the voltage meter V according closing the measurement switch s2 (Fig. 1 at time t₂ ) further the characteristic voltage waveform lUar of the measurement system 2. The charging circuit discharges over only the internal resistance R of the 5 thus further voltage measurement apparatus of V, it occurs not hopping channel of the voltage waveform.

The electrical system 1 is contacted, the measuring system is such 2, consisting of the charging circuit and the voltage meter 5 extended V with internal resistance R for closing the measurement switch 2 the electrical system 1. This enlargement of the measurement system to the impedance of the impedance 2 electrical system 1 is extended so that the total impedance and it changes, via which the discharge current flows. This also causes a change in the voltage waveform at the voltage meter V to the U, as in Figure. 2b and Figure. 2c is outlined below describe in detail and. Thus can be closed on a successful contact.

Advantageously the measurement switch is closed s2, when a as in Figure. 2 voltage threshold represented a U_seconds on closing the discharge switch is below a V voltage meter according s1. Thus resulting in damage to sensitive electronic measuring system 2 for example by current spikes can be avoided.

In addition to the voltage measuring device can V to internal resistance Ri as in the Figure. 3 represented a discharge resistor R are used, to influence the voltage waveform U and thus the course of the characteristic voltage LUar of the measurement system 2, in particular a time constant, . A coupling the discharge resistance R is for reducing the impedance of the measurement system causes voltage meter volts and thus reducing currently constant. Thus a faster curve shape is achieved.

In the case of a series circuit of the discharge resistor R is for voltage meter V the impedance of the measurement system 2 and thus increases the time constant while, but also the maximum current is also reduced, which causes a protection for sensitive electronic components.

The charging circuit as shown in Figure 3. can for example represented as voltage or current source Q is - be embodied, a charging switch connected in parallel to a disposable over s3 capacitance C. After closing the charging switch s3 the capacity c is loaded.

After the discharge switch is opened then s1, the charged capacitance can be discharged via the voltage meter V to invention. S1 the discharge switch can also be closed, if the charging switch s2 is still closed. To ensure discharge of the charging circuit 5, the charging switch should be opened some time but always s3 already, when the measuring system 5 is switched with the measurement switch on the electrical circuit 1 s2. When the discharging operation of the charging circuit 5 does not start before closing the measurement switch, it would not be possible to receive the characteristic voltage waveform LUar the charging circuit 5, since the electrical system would have already changed the total impedance.

The voltage measured by the voltage meter volts can be evaluated in an evaluation unit can be displayed on a display unit 6 and 7. The measured voltage in the evaluation unit can be digitized to of course in known manner.

The output impedance of the electrical system 1, which is located between the measuring contacts 4, is usually low. Thus the voltage U falls in the case of a successfully contacted, but between the measuring points 3 stress free electrical system 1 according to closing the measuring time t switch s2₂ at the voltage meter volts from strong, as in Figure. 2b represented. It is because of the sunken total impedance, on the discharges the charging circuit 5, composed of electrical system of the measuring circuit 1 and 2.

The electrical system 1 is loaded and electrically contacted, so that the course of the voltage U rises to closing the measuring time t switch s2₂ at the voltage meter V to strongly, as in Figure. 2c is to see.

Thus cannot only be concluded that there is a correct contact, but also, whether the electrical system in the event of a successful contact is under tension, or is stress-free. Advantageously is used for detecting the presence of a voltage at the measuring points 3 V to the voltage measuring apparatus.

The method and the device can thus also measure the voltage present at the measuring points 3, the implementation of a voltage measurement mode or a voltage measuring device what corresponds to detection of successful contacting and openable.. according to a detection voltage with the voltage measuring apparatus to measure the discharge switch s1 V the measuring voltage applied to the contacts. This sequence can also be carried out automatically, i.e. the correct contact is first detected and the voltage measurement performed before a voltage measurement always only, when the contact was made.